Apparatus for chemical vapor deposition (cvd) with showerhead

ABSTRACT

Disclosed therein is a method of chemical vapor deposition (CVD) with a showerhead through which a source material gas comprising a reactive gas of at least one kind and a purge gas is injected over a substrate to deposit a film on the substrate, including the steps of: disposing the showerhead in such a way that the bottom surface of the showerhead is spaced apart from the substrate by a predetermined distance; supplying a source material gas into the showerhead, wherein reactive gases of different kinds are respectively injected into compartments formed inside the showerhead in such a way that each compartment of the showerhead is filled with the reactive gas of only one kind and a purge gas of the source material gas is supplied into another compartment formed inside the showerhead; and discharging the reactive gas and the purge gas respectively through a large number of reactive gas outlets and a large number of purge gas outlets formed on the bottom surface of the showerhead, the purge gas outlets being more in number than the reactive gas outlets.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for chemical vapordeposition (CVD) that is one of effective means for forming a film on asemiconductor integrated circuit, a fine mechanical structure, or a toolwhich requires surface treatments, and more particularly, to anapparatus for chemical vapor deposition (CVD) with a showerhead andmethod thereof, that can prevent a undesired particle deposition on theshowerhead which supplies reactive gases uniformly over a substrate togrow a uniform film on the substrate in thickness and composition. Here,the present invention is associated with U.S. Patent Laid-OpenPublication No. 2003-0077388 (“Method And Apparatus For Chemical VaporDeposition Capable Of Preventing Contamination And Enhancing Film GrowthRate” filed on Oct. 9, 2002), the entire contents of which are herebyincorporated by reference.

2. Background Art

In an apparatus for chemical vapor deposition (CVD), a reactive gas isintroduced into a vacuum reaction chamber, passes through a showerhead,then reaches a susceptor or a substrate holder on which a substrate islocated.

Therefore, the reactive gas causes chemical reaction on the substrate toform a desired film. As means to provide energy necessary to inducechemical reactions on the substrate, a method of simply heating thesubstrate or atomically exciting the reactive gas, such as makingplasma, is widely used. After the reaction is finished, byproduct gasesare removed from the reaction chamber by an exhaust system including avacuum pump, passes through a purifying system, then discharged into theatmosphere. However, since it is very important to prevent undesiredparticle deposition on a wall of the reaction chamber or the showerheadduring a deposition process, it is preferable that the reactive gases donot react each other in a gaseous state. Unfortunately, if reactivegases whose decomposition temperature are substantially lower than 200°C. like metal-organic compounds are mixed in the reaction chamber, themixture may cause homogeneous reactions in the gas phase so as togenerate contaminant particles, or cause heterogeneous reactions on asolid-state surface, such as the showerhead surface or the reactionchamber wall so as to deposit undesired particles. Particularly, it mayhappen that the reactive gas is sensitive to a specific material, forexample, zirconium tert-butoxide (Zr(OC₄H₉)₄) is extremely sensitive tomoisture so as to form zirconium hydroxide (Zr(OH)_(x)) which is apowder. The moisture could have been physically adsorbed on the innerside of the reaction chamber but it may be also generated over thesubstrates as a byproduct gas.

Such moisture reacts with Zr(OC₄H₉)₄ on the inner wall of the reactionchamber or the surface of the showerhead, depositing a zirconiumhydroxides of white powder type on the surface thereof. Then, thedeposited particles are flaked off into fine particles due to a repeatedthermal expansion and contraction and/or a lattice parameter mismatchwith the inner wall of the reaction chamber. As a result of this, thefilm formed on the substrate may be contaminated and the productivitymay be lowered due to a shortened process management cycle time forremoving the deposited particles.

When a highly integrated semiconductor is manufactured, contaminantparticles may cause a pattern defect such as short or disconnectionbetween lines, and a size of the contaminant particle influencing onyield is in proportion to the line width. Therefore, as the line sizebecomes smaller, that is, as the density of the integration isincreased, the size of particle influencing on yield becomes alsosmaller, whereby the number of contaminant particles to be controlled inthe reaction chamber is more seriously limited.

FIG. 1 is a brief sectional view of a reaction chamber of a conventionalplate type plasma CVD apparatus using a simple showerhead having a largenumber of holes as described in U.S. Pat. No. 6,631,692. When thereaction chamber is maintained in a vacuum state by a vacuum pump (notshown), material gases, that is, reactive gases flowing from a materialgas supply tank is controlled by a mass flow controller 8 at apreferable flow rate, and the material gas delivered into a showerhead20 is supplied on a substrate through fine holes formed on the bottomsurface of the showerhead after being mixed sufficiently. After a flowis stabilized, a radio frequency (RF) electric field is generatedbetween the showerhead 20 connected to an RF power source 4 and asusceptor grounded to an earth 13, and then, the material gas is ionizedand the plasma state occurs. Atoms of the ionized material gas shows achemical reaction on a semiconductor substrate 9 located on thesusceptor 30, which keeps temperature of the substrate higher than thatof surroundings using a substrate heater 14 embedded in the reactionchamber, whereby a desirable film is formed on the substrate 9. As amaterial gas, the silicon source gases such as SiH₄,DM-DMOS[(CH₃)₂Si(OCH₃)₂], and TEOS, fluorine source gases such as C₂F₆,oxidizing gases such as oxygen, and inert gases such as Ar and He can beused.

There may be no serious problem when one of the above raw materials isused solely, but in case when a specific material, for example,metal-organic compound of a low decomposition temperature, is used asthe material gas, the material gas may cause chemical reaction insidethe showerhead or generate contaminant particles by decomposing byitself, thereby contaminating the inside of the reaction chamber and thesurface of the substrate.

FIG. 2 shows a schematic sectional view of a showerhead of a prior art,U.S. Pat. No. 6,626,998, that has a function to uniformly spray reactivegas, which is introduced into a reaction chamber, over a substratethrough a plurality of outlets without gas mixing. When each reactivegas is supplied to first ring type individual channels 23 through aplurality of gas supply passages 17, the gases are diffused in the firstindividual channels 23, and then, transmitted to second ring typeindividual channels 27 through a plurality of transition passages 25formed on the bottom of each channel. After diffusion of the reactivegases in the second channels 27, the gases are supplied over a substratethrough a plurality of second gas transition passages 31 which areformed on the bottom of the second channels. The reactive gases causechemical reaction on the substrate (not shown) placed on a susceptorkeeping temperature of the substrate higher than that of surroundings soas to form a desired film on the substrate.

However, a reactive gas such as metal-organic compound gas which has adecomposition temperature of about 200□ or below may cause heterogeneoussurface reactions including a thermal decomposition on the bottomsurface of the showerhead, and particularly, if the reactive gas issensitive to a specific material like moisture, the reactive gas mayform unwanted deposits on the bottom of the showerhead by combining withthe moisture produced as a byproduct.

With regard to the contamination path described above, FIG. 3 shows thatthe reactive gas or byproduct gas may reversely diffuse toward theshowerhead in case that there is not provided suitable suppressingmeans. In FIG. 3, a thin arrow indicates an average drift flow of thereactive gases, and a thick arrow indicates a reverse diffusiondirection of the reactive gases or byproducts toward the showerhead. Thebyproducts generated over the substrate may be reversely diffused towarda zone 8 existing between the showerhead and the substrate, and thegases in the zone 8 may be also reversely diffused toward theshowerhead. Therefore, even if the conventional showerhead device shownin FIG. 2 may prevent each reactive gas from being mixed inside theshowerhead and generating particles, in case that there is not providedsuitable suppressing means, undesired particles may be deposited on thebottom of the showerhead by thermal decompositions or other chemicalreactions. And this problem is especially serious if the substratetemperature becomes higher.

A necessity to form various kinds of films using various kinds ofreactive gases by CVD process has been increased. However, if theconventional showerhead device is used further, undesired particles maydeposit on the bottom of the showerhead due to the unexpected propertiesof the reactive gases used, which may limit the wide application of theCVD process.

SUMMARY OF THE INVENTION

Accordingly, to solve the above disadvantages of the prior arts, it isan object of the present invention to provide an apparatus for chemicalvapor deposition (CVD) with a showerhead and method thereof, which canindependently deliver each reactive gas through the showerhead, therebypreventing the reactive gases from causing chemical reaction andgenerating unwanted particles inside the showerhead.

It is another object of the present invention to provide an apparatusfor chemical vapor deposition (CVD) with a showerhead and methodthereof, which allows the purge gas to be injected from the bottomsurface of the showerhead and to form a concentric flow by surroundingthe flow of the reactive gas which is simultaneously jetted from thebottom surface of the showerhead, thereby preventing diffusion of thereactive gas backwardly, and preventing unwanted particle deposition onthe outlet and the bottom surface of the showerhead.

It is a further object of the present invention to provide an apparatusfor chemical vapor deposition (CVD) with a showerhead and methodthereof, applied to a reactive gas confining means which surrounds thesubstrate and touches the bottom of the reaction chamber at its one end,thereby preventing undesired particle deposition on the inner wall ofthe reaction chamber and enhancing film growth rates on the substratesby confining the reactive gas in the vicinity of the substrate.

To accomplish the above mentioned objects, in an aspect of the presentinvention, there is provided a method of chemical vapor deposition(CVD), which supplies a source material gas over a substrate through ashowerhead to deposit a film on the substrate, comprising the steps of:disposing a showerhead in such a way that the bottom surface of theshowerhead is spaced apart from the substrate by a predetermineddistance; supplying a source material comprising a reactive gas of atleast one kind and a purge gas into the showerhead, wherein reactivegases of different kinds are respectively supplied into compartmentsformed inside the showerhead in such a way that each compartment of theshowerhead is filled with the reactive gas of only one kind, and a purgegas is supplied into another compartment formed inside the showerhead;and injecting the reactive gas and the purge gas respectively through alarge number of reactive gas outlets and a large number of purge gasoutlets formed on the bottom surface of the showerhead, the purge gasoutlets being more in number than the reactive gas outlets.

In another aspect of the present invention, there is provided anapparatus for chemical vapor deposition (CVD) with a showerhead, whichsupplies a source material gas comprising a reactive gas of at least onekind and a purge gas over a substrate through the showerhead to deposita film on the substrate, wherein the showerhead includes: a plurality ofreactive gas showerhead modules of the same number as the kinds ofreactive gases, each of the reactive gas showerhead module having aninner space separated from each other and a large number of reactive gasflow channels connected to the bottom surface thereof for injecting thereactive gas over the substrate; and a purge gas showerhead modulemounted under the reactive gas showerhead modules, having a purge gassupply port for supplying a purge gas thereto, an inner space separatedfrom inner spaces of the reactive gas showerhead modules for beingfilled with the purge gas only, a large number of inlets formed on theupper surface thereof for allowing a penetration of the said reactivegas flow channels through the inner space thereof with hermetic sealingat the joints thereof, and a large number of exits for reactive gas flowchannels and a large number of exits for purge gas on the bottom surfacethereof, each purge gas exit having a diameter smaller than that of thereactive gas flow channel exit, and wherein each reactive gas flowchannel of each reactive gas showerhead module placed at upper positionspasses through the inside of the other reactive gas showerhead modulesplaced at lower positions as well as the inside of the purge gasshowerhead module.

In a further aspect of the present invention, there is provided anapparatus for chemical vapor deposition (CVD) with a showerhead, whichsupplies a source material gas comprising a reactive gas of at least onekind and a purge gas over a substrate through the showerhead to deposita film on the substrate, wherein the showerhead includes: a reactive gasshowerhead module, of which inner space is divided into a plurality ofseparated compartments to introduce different kinds of reactive gasesseparately and alternatively through a reactive gas supply port formedon each compartment, having a plurality of reactive gas delivering holesformed on a bottom surface of each compartment and reactive gas flowchannels connected to every reactive gas delivering hole for supplyingreactive gases over the substrate; and a purge gas showerhead modulemounted under the reactive gas showerhead module, of which inner spaceis separated from the said reactive gas showerhead module and filledwith the purge gas through a purge gas supply port formed therein,having a large number of inlets formed on the upper surface thereof forallowing a penetration of the said reactive gas flow channels throughthe inner space thereof with hermetic sealing at the joints thereof,having a large number of exits for the said reactive gas flow channelsand a large number of exits for the said purge gas on the bottom surfacethereof, and wherein each purge gas exit has a diameter smaller thanthat of the reactive gas flow channel exit.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be apparent from the following detailed description ofthe preferred embodiments of the invention in conjunction with theaccompanying drawings, in which:

FIG. 1 is a brief sectional view showing a reaction chamber of aconventional plate type plasma CVD apparatus using a simple showerheadhaving a large number of exit holes;

FIG. 2 is a brief sectional view showing a conventional showerhead foruniformly injecting reactive gases over a substrate through a largenumber of outlets without reactive gas mixing therein;

FIG. 3 is an exemplary view showing that the reactive gas or byproductgas may reversely diffuse toward the showerhead in case that there isnot provided suitable suppressing means;

FIG. 4 is an exploded perspective view of a first embodiment accordingto the present invention including a plurality of reactive gasshowerhead modules vertically laid on another and a purge gas showerheadmodule;

FIG. 5 is a sectional view of the first embodiment according to thepresent invention including a plurality of reactive gas showerheadmodules vertically laid on another and a purge gas showerhead module;

FIG. 6 is a bottom view seen from the bottom side of the purge gasshowerhead module according to the first embodiment of a showerhead ofthe present invention;

FIG. 7 is an exemplary view of the first embodiment of a showerheadaccording to the present invention, showing flow directions of areactive gas and a purge gas injected from the showerhead;

FIG. 8 is an exemplary view of the first embodiment of a showerheadaccording to the present invention, showing flow directions of areactive gas and a purge gas injected from the showerhead where reactivegas flow channel exits are extended toward the substrate by apre-determined length;

FIG. 9 is an exploded perspective view of a second embodiment of ashowerhead according to the present invention including a reactive gasshowerhead module with compartments divided by vertical partitions and apurge gas showerhead module;

FIG. 10 is a sectional view of the second embodiment of a showerheadaccording to the present invention including a reactive gas showerheadmodule having compartments divided by vertical partitions and a purgegas showerhead module;

FIG. 11 is a bottom view seen from the bottom side of the purge gasshowerhead module according to the second embodiment of the presentinvention;

FIG. 12 is an exemplary view of compartments of a sliced cake shapeaccording to the second embodiment of the present invention;

FIG. 13 is an exemplary view of compartments of a modified sliced cakeshape according to the second embodiment of the present invention;

FIG. 14 is an exemplary view of compartments of a modified sliced cakeshape in which locations of reactive gas flow channels are shifted by apredetermined distance along the radial direction according to thesecond embodiment of the present invention;

FIG. 15 is an exemplary view showing a configuration where theshowerhead according to the present invention is applied to a reactivegas confining means;

FIG. 16 is an exemplary view of the conventional CVD apparatus equippedwith a reactive gas confining means on which the effect of the presentinvention does not exert;

FIG. 17 is an exemplary view showing a configuration where theshowerhead according to the present invention is applied to anotherreactive gas confining means; and

FIG. 18 is an exemplary view showing a configuration having acylindrical cooling jacket surrounding the showerhead according toanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As described above each reactive gas passes through a showerheadindependently in the present invention, thereby preventing mixing of thereactive gases inside the showerhead, and the backward diffusion of thereactive gas and byproducts toward the showerhead is suppressed by asimultaneous jetting of purge gas from the bottom of the showerhead,thereby preventing unwanted deposition of particles on outlets andbottom surfaces of the showerhead. Moreover, the present invention wasapplied to a “reactive gas confining means” claimed in U.S. PatentLaid-Open Publication No. 2003-0077388 (“Method And Apparatus ForChemical Vapor Deposition Capable Of Preventing Contamination AndEnhancing Film Growth Rate” filed on Oct. 9, 2002), thereby enhancingfilm growth rates on substrates as well as preventing both of reactionchamber inner wall and showerhead itself from unwanted particledeposition.

The purge gas doesn't either dissolve or generate byproducts by itself.For example, the purge gas includes Ar, N₂, and He. In addition to this,H₂ or O₂ may be included as a purge gas too, since it does not dissolveor generate byproducts by itself but may participate in the depositionprocess as a reactant. The purge gas, having a relatively smallmolecular weight, diffuses instantly in the reaction chamber and isrelatively little influenced by a force circulation done by the act ofvacuum pumping, and does not cause deposition or surface reaction on theinner structure of the reaction chamber.

Meanwhile, the reactive gas is a source material of vapor phase thatparticipates directly in forming the film by pyrolysis, combination, andetc.; a mixture of vapor phase containing a main source material andcarrier gas for vaporizing or diluting the main source material; or apurely vaporized main source material without the aid of carrier gas.The main source material includes, for example, Pb(C₂H₅)₄ which is asource material of Pb, Zr(OC₄H₉)₄ which is a source material of Zr, andTi(OC₃H₇)₄ which is a source material of Ti, which are metal-organiccompounds for the deposition of PZT (Lead Zirconium-Titanate) films. Thecarrier gas includes, for example, Ar, N₂, He, H₂ etc. The reactive gascauses adsorption and surface reaction on all of the inner structure ofthe reaction chamber which includes substrates, the reaction chamberinner wall, and the showerhead.

FIGS. 4 a to 4 e show a first embodiment of a showerhead including aplurality of reactive gas showerhead modules and one purge gasshowerhead module, wherein FIG. 4 is an exploded perspective viewshowing a state before assembly, and FIG. 5 is a sectional view of anassembled state, FIG. 6 is a bottom view of the showerhead. Theshowerhead 100 includes a plurality of the reactive gas showerheadmodules 140 and 240 corresponding to the number of reactive gases, andone purge gas showerhead module 440. In the present invention, thereactive gas showerhead module means an assembly including at least onemodule for diffusing and delivering one of reactive gases. In the firstembodiment of the present invention, reactive gases of two kinds areused.

One reactive gas is introduced into the upper reactive gas showerheadmodule 140 through an inlet 153 thereof, sufficiently diffused insidethe reactive gas showerhead module 140 while passing through a diffusionplate 157 having a large number of fine holes, and then discharged fromthe reactive gas showerhead module 140 along a large number of holes 143of the reactive gas showerhead module 140. Another reactive gas isintroduced into the lower reactive gas showerhead module 240 through aninlet 253 thereof, and so on. A circular tube type reactive gas flowchannel 144 is connected to each hole 143, and extends through the lowerreactive gas showerhead module 240 located under the upper reactive gasshowerhead module 140. The reactive gas flow channels 144 and 244respectively extended from the reactive gas showerhead modules 140 and240 finally pass through the upper surface 447 and the inside of thepurge gas showerhead module 440. The purge gas is introduced into thepurge gas showerhead module 440 through a purge gas inlet 453 thereof,sufficiently diffused inside the purge gas showerhead module 440 whilepassing through a diffusion plate 457 having a large number of fineholes, and then, reaches a purge gas showerhead module bottom 442.

Meanwhile, the purge gas showerhead module bottom 442 includes a largenumber of relatively large size exits 445 for surrounding end tips ofreactive gas flow channels and a large number of relatively small sizeexits 446 for injecting purge gas only. The tube type gas flow channels144 and 244 which pass through the upper surface 447 and penetrate theinside of the purge gas showerhead module 440 come to an end at the openended area of the exits 445.

In this structure, the reactive gas is injected toward the substratefrom the ends of the reactive gas flow channels 144 and 244 located atthe central area of the reactive gas flow channel exit 445 of largesize, and the purge gas is injected toward the substrate along an edgearea of the reactive gas flow channel exit 445 of large size, namely,along a gap formed between the inner wall of the reactive gas flowchannel exit 445 and the outer wall of the reactive gas flow channels144 and 244 so that the purge gas is concentrically injected bysurrounding the reactive gas. Here, the end tip of the reactive gas flowchannels 144 and 244 are 0 to 3 mm indented or protruded from the endtip of the reactive gas flow channel exits 445 so as to effectivelyprevent contamination due to unwanted particle deposition on both of thereactive gas flow channels 144 and 244 and the reactive gas flow channelexit 445.

Meanwhile, only purge gas is injected toward the substrate through thepurge gas exit 446 of small area. Owing to above operations of the purgegas, the prevention of unwanted particle deposition on the bottomsurface of the purge gas showerhead module 440, reactive gas flowchannel exit 445, and reactive gas flow channels 144 and 244 isaccomplished. The total flow rate of the purge gas is externallycontrolled and would be several times as much as that of the reactivegas.

FIG. 7 shows an injection pattern of the reactive gas and the purge gasnear the bottom surface of the purge gas showerhead module. It isdesirable that a flow rate of the purge gas injected through a reactivegas flow channel exit 445 is higher than that of the purge gas injectedthrough a purge gas exit 446. It is desirable that the arrangementinterval between the reactive gas flow channel exit 445 on the bottomsurface of the purge gas showerhead module 440 is about 10 mm along bothof the X and Y directions in the bottom surface, so that the number ofthe reactive gas flow channel exits 445 is about 250 for a 200 mm waferand about 500 for a 300 mm wafer, and that a inner diameter of thereactive gas flow channel exit 445 is 3.5 mm to 5 mm.

Moreover, it is desirable that the purge gas exits 446 are arranged atproper intervals among the reactive gas flow channel exits 445, and thediameter of the purge gas exit is 0.8 mm˜1.4 mm. However, thearrangement intervals and the number of the exits are not restricted toabove values, but may be determined based on fabrication difficultiesand required specifications such as uniformity.

Meanwhile, as shown in FIG. 8, it is preferable that the reactive gasflow channel exit 445 is extended for a proper distance towards thesubstrate (not shown) by connecting a tube type exit extension 444 tothe reactive gas flow channel exit 445. Concretely, if an end tip of theexit extension 444 is extended for 0˜10 mm from the bottom surface ofthe purge gas showerhead module 440, it could be more effective in theprevention of contamination caused by unwanted particle deposition onthe bottom surface of the purge gas showerhead module.

In the fabrication of the showerhead, it is preferable to join thereactive gas flow channels 144 to the holes 143 of the bottom surface142 by laser welding. Additionally, O-ring 276 may be used to make ahermetic sealing between the reactive gas flow channel 144 andcorresponding faces 142, 247, 242, or 447 of the showerhead module.Here, it is good that the O-ring groove 275 is prepared to have an innerdiameter larger than the outer diameter of the O-ring 276 by 0.2 mm to0.3 mm, and a depth smaller than the thickness of the O-ring by 0.6 to0.9 mm.

In the assembling process for the present invention, the showerheadmodules 140, 240, and 440 are tightened together by bolts 501. Then, ahermetic sealing between the reactive gas channels 144 and the uppersurface of the lower reactive gas showerhead module 240 is done by theeffect of pressed O-ring 276. Thereby, the inner spaces of showerheadmodules 140, 240 and 440 are separated from each other.

The reactive gas supplied along the reactive gas flow channels 144 isnot mixed with another reactive gas or the purge gas, until it isinjected from the end tip of the reactive gas flow channel 144, then,mixed with another reactive gas and the purge gas at the space betweenthe bottom surface 442 of the purge gas showerhead module 440 and thesubstrate (not shown).

Meanwhile, the exit extension 444 connected to the reactive gas flowchannel exit 445 may not have an annular section but have a modifiedshape such as hollow polygon section. Then, the modified shape may beapplied if such structure could maintain the concentric flow of thepurge gas by surrounding the reactive gas flow. Therefore, as far as aslight modification to the present configuration provides a similareffect, the present invention is not restricted to the depictedconfigurations.

Meanwhile, to achieve the best uniformity in depositions, it ispreferred that the bottom surface 442 of the purge gas showerhead module440 and the substrate (not shown) be spaced apart from each other by apredetermined distance, and it is preferable that the distance is 70 mm120 mm.

FIGS. 5 a to 5 f show the second embodiment of the present invention. Inthis embodiment the showerhead comprises two showerhead modules, thatis, one reactive gas showerhead module 640 and one purge gas showerheadmodule 740. The reactive gas is distributed into a plurality of tubetype reactive gas supply conduits (not shown) through distribution heads(not shown), the tube type reactive gas supply conduits are connected toa plurality of supply ports 655 disposed on the upper surface of thereactive gas showerhead module 640 in proper order.

Each supply port 655 is respectively connected to a compartment 656which has a sliced cake shape in the reactive gas showerhead module.Each reactive gas is separately and alternately introduced into eachcompartment 656 which is hermetically sealed each other by a seal 658,then reaches the bottom surface of each compartment 656, through adiffusion plate 657 located inside each compartment 656. The bottomsurface of each compartment 656 includes a plurality of holes 643 of thereactive gas showerhead module 640. Cylindrical tube type reactive gasflow channels 644 are connected to the holes 643, then pass through theupper surface 747 and penetrate the inside of the purge gas showerheadmodule 740. The purge gas is introduced into the purge gas showerheadmodule 740 through a purge gas inlet 753 of the purge gas showerheadmodule 740, sufficiently diffused inside the purge gas showerhead module740 while passing through the diffusion plate 757 having a large numberof fine holes, and then, reaches the bottom surface 742 of the purge gasshowerhead module. The structure of the bottom surface 742 of the purgegas showerhead module, connection method and structure between thereactive gas flow channel 644 and the bottom surface 742 of the purgegas showerhead module, and effects of the showerhead are sufficientlydescribed in the first embodiment of the present invention, and so,their repeated description will be omitted here.

In FIG. 9, the number of the compartments 656 disposed in the reactivegas showerhead module 640 is four. Of course, the number of thecompartments 656 may be increased if necessary, but it is preferablethat 24 compartments are arranged at an angle of 15 degrees. Here, ifthere are two kinds of reactive gases, the reactive gases are introducedinto twelve compartments 656 in turn, but if there are three reactivegases, the reactive gases are introduced into eight compartments 656 inturn.

FIG. 12 shows sliced cake shape compartments 656. However, FIG. 13 showsmodified sliced cake shape compartments 656 having a section graduallyshifted in a circumferential direction, and conceptually shows thatthree kinds of reactive gases A, B and C are introduced into thereactive gas showerhead module 640 in turn.

In FIG. 13 the arrangement of the reactive gas flow channel 644 does nothave a specific direction such as radial direction, but is stepped anddistorted circumferentially along the center of arrangement, so that theuniformity of the growing films would be enhanced in the circumferentialdirection.

In the same way, as shown in FIG. 14, as the compartments 656 arerepeatedly arranged along the circumferential direction (A and A′, B andB′, C and C′), locations of the reactive gas flow channels 644 formed onbottom of the compartments 656 are, compared to expected locations byrepetition, offset by a predetermined distance (Δr in FIG. 14) towardthe radial direction, so that the uniformity of the growing films wouldbe enhanced in the radial direction.

EXAMPLE 1

FIG. 15 shows the first example where the showerhead 100 of the presentinvention is applied to a reactive gas confining means 900. Here, thereactive gas confining means 900 is spaced apart from the inner wall 7and the ceiling of the reaction chamber 1 at a distance, surrounds thesubstrate 9 with a dome-like roof, touches the bottom 961 of thereaction chamber along its end, has a large number of fine holes formedthereon and an opening formed at the central portion of the roof thereofon which the rim of the showerhead 100 is placed along the opening sothat the bottom surface of the showerhead 100 and the substrate are inparallel to and facing each other.

As shown in FIG. 15 of the first example, the reactive gas is introducedinto the showerhead 100 through a reactive gas supply port 954, adistribution head 958, and a reactive gas supply conduit 959, and afirst purge gas is introduced into the showerhead 100 through a firstpurge gas supply conduit 964. Then, the present invention accomplishesprevention of unwanted particle deposition on the surfaces of theshowerhead. Meanwhile, a second purge gas is introduced to the outsideof the reactive gas confining means 900 through a second purge gassupply port 962, then introduced to inside of the reactive gas confiningmeans 900 through the second purge gas flow channels 901 formed acrossthe reactive gas confining means 900, whereby such configuration canprevent unwanted particle deposition on the surface of the reactive gasconfining means 900 and the inner wall 7 of the reaction chamber 1 aswell.

Furthermore, in the first example, the reactive gas is confined in thevicinity of the substrate, that is, the reactive gas is highlyconcentrated at a region just over the substrate, so that a film growthrate is increased on the substrate. Moreover, compared to theconventional bubbler system or a liquid delivery system in whichprecursor delivery is done with the aid of carrier gas, the reactive gasmay comprise only main source material gas such as purely vaporizedsource material without the aid of a carrier gas. For example,metal-organic compound at liquid phase, the source material in MOCVD(Metal Organic Chemical Vapor Deposition), may be converted to a purevapor and be forced into the reaction chamber by being heated attemperatures of about 60-100□ if its equilibrium vapor pressure is highenough. In this case, as described in U.S. Patent Publication No.2003-0077388, the enhancement effect of film growth rates on substratesbecomes more distinct by the cooperation of the reactive gas comprisingpure vapors and the second purge gas doing confinements.

FIG. 16 is an exemplary view showing a prior art CVD apparatus to whichthe present invention is not applied. In FIG. 16, outlets of a pluralityof source material supply conduits 907 are formed inside the reactivegas confining means 900 as disclosed in U.S. Patent Publication No.2003-0077388.

However, U.S. Patent Publication No. 2003-0077388 cannot propose amethod for preventing contamination at areas of the end tips of thesource material supply conduits 907. In this regards it is highlyrequested that the present invention be applied to the reactive gasconfining means disclosed in U.S. Patent Publication No. 2003-0077388 toassure high film growth rates on substrates and to prevent contaminationof reaction chamber internal structures including a reaction chamberinner wall and a showerhead.

EXAMPLE 2

FIG. 17 shows the second example where the showerhead 100 configuredaccording to the present invention is applied to a reactive gasconfining means 900. Here, the reactive gas confining means 900 isspaced apart from the inner wall 7 and the ceiling of the reactionchamber 1 at a distance, surrounds the substrate 9 in a cylindrical formwith no roof, touches the bottom 961 of the reaction chamber at one itsend thereof, has a large number of fine holes formed thereon. A disc 968having a large opening at the center thereof is placed on the upperportion of the reactive gas confining means, so that the rim of theshowerhead 100 is placed on the central portion of the disc 968 and thebottom surface of the showerhead 100 and the substrate are in parallelto and facing each other.

As shown in FIG. 17 of the second example, the second purge gas isintroduced to the outside of the reactive gas confining means 900through a purge gas supply port 962 connected to the reaction chamber 1and perforated holes across disc 968, then, introduced to inside of thereactive gas confining means 900 through the second purge gas flowchannels 901 formed across the surface of the reactive gas confiningmeans 900. Functions and effects in this second example of the presentinvention are sufficiently described in the first example of the presentinvention, so that their repeated description will be omitted here.

EXAMPLE 3

As shown in FIG. 18, a cooling jacket 3050 is mounted by surrounding thepart of vertical wall of the showerhead. The cooling jacket 3050 has afunction to keep temperature of the showerhead at steady state, forexample, at temperature of 150□˜200□.

A refrigerant supplied into the cooling jacket 3050 through arefrigerant supply port 3054 of the cooling jacket 3050 cools theshowerhead properly and finally goes out from the reaction chamber alonga discharge channel (not shown) connected to a refrigerant outlet port3053. Here, the refrigerant may be one of compressed air, cooling water,and so on, and it is very important to assure the prevention of arefrigerant leakage from the cooling jacket and the connected dischargechannel to the reaction chamber. A thermocouple (not shown) may bemounted at any proper place of the surface of the showerhead to measureand control showerhead temperature. Since it may belong to a generalmethod, detailed description will be omitted here. The cooling jackettechnology in the present invention serves not only for enhancingreproducibility in film deposition process but also for preventingunwanted film deposition at the showerhead by thermal decomposition ofthe reactive gas caused by unnecessarily high temperature of theshowerhead.

As described above the present invention has a function that eachreactive gas passes through a showerhead independently, therebypreventing mixing of the reactive gases inside the showerhead.

Furthermore, the present invention has a function that the purge gas isinjected from the bottom surface of the showerhead and forms aconcentric flow by surrounding the flow of the reactive gas which issimultaneously jetted from the bottom surface of the showerhead, therebypreventing diffusion of the reactive gas backwardly, and preventingunwanted particle deposition on the outlet holes and the bottom surfaceof the showerhead.

Moreover, the present invention has a configuration that a coolingjacket is mounted around the wall of the showerhead wall, therebymaintaining temperature of the showerhead at steady state and preventingunwanted film deposition caused by thermal decomposition of the reactivegases.

Additionally if the present invention is applied to a CVD systemtogether with a reactive gas confining means, unwanted particledeposition on the reaction chamber inner wall as well as on theshowerhead is prevented and process managing cycle time to remove theparticle is lengthened much.

In addition if the present invention is applied to a CVD system togetherwith a reactive gas confining means, the reactive gas is confined in thevicinity of the substrate, thereby the film growth rate is increasedcompared to the process which does not use a reactive gas confiningmeans.

While the present invention has been described with reference to theparticular illustrative embodiments, it is not to be restricted by theembodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

1-33. (canceled)
 34. An apparatus for chemical vapor deposition (CVD)with a showerhead through which a source of material gas comprising areactive gas of at least one kind and a purge gas is injected over asubstrate located in a reaction chamber to deposit a film on thesubstrate, wherein the showerhead includes: a plurality of reactive gasshowerhead modules of the same number as the kinds of reactive gases ofthe source material gas, each of the said reactive gas showerhead modulehaving an inner space separated from each other and a plurality ofreactive gas flow channels connected to the bottom surface thereof forinjecting the reactive gas over the substrate; and a purge gasshowerhead module mounted under the reactive gas showerhead modules,having a purge gas supply port for supplying a purge gas of the sourcematerial gas thereto, an inner space separated from inner spaces of thereactive gas showerhead modules for being filled with the purge gasonly, a plurality of inlets formed on the upper surface thereof forallowing a penetration of the said reactive gas flow channels theretowith hermetic sealing at joints of the said inlets, a plurality of exitsfor said reactive gas flow channels and a plurality of exits for saidpurge gas formed on the bottom surface thereof, and said exit for purgegas having a diameter smaller than that of said exit for the reactivegas flow channel, and wherein each reactive gas flow channel of eachreactive gas showerhead module placed at upper positions passes throughthe inside of the other reactive gas showerhead modules placed at lowerpositions and through the said inner space of the purge gas showerheadmodule.
 35. An apparatus for chemical vapor deposition (CVD) with ashowerhead according to claim 34, wherein the purge gas exit is 0.8mm˜1.4 mm in diameter and the reactive gas flow channel exit is 3.5 mm˜5mm in diameter, and wherein the purge gas exit injects only the purgegas and the reactive gas flow channel exit injects the purge gas bysurrounding the lower end of the reactive gas flow channel.
 36. Anapparatus for chemical vapor deposition (CVD) with a showerheadaccording to claim 34, wherein the reactive gas is a mixture of avaporized material containing compositions of the film deposited and acarrier gas for vaporizing said material in an evaporator.
 37. Anapparatus for chemical vapor deposition (CVD) with a showerheadaccording to claim 34, wherein the reactive gas showerhead modulefurther includes a porous diffusion plate therein.
 38. An apparatus forchemical vapor deposition (CVD) with a showerhead according to claim 34,further comprising a cooling jacket for surrounding and cooling theshowerhead using a refrigerant.
 39. An apparatus for chemical vapordeposition (CVD) with a showerhead through which a source material gascomprising a reactive gas of at least one kind and a purge gas isinjected over a substrate located in a reaction chamber to deposit afilm on the substrate, wherein the showerhead includes: a reactive gasshowerhead module having an inner space divided into a plurality ofseparate compartments for introducing different kinds of reactive gasesseparately and alternatively through a reactive gas supply port formedon each compartment, a plurality of reactive gas delivering holes formedon a bottom surface of each compartment, and reactive gas flow channelsconnected to said every reactive gas delivering hole for injectingreactive gases over the substrate; and a purge gas showerhead modulemounted under the reactive gas showerhead module, having a purge gassupply port for introducing a purge gas of the source material gasthereto, an inner space separated from the said inner space of thereactive gas showerhead module for being filled with the purge gas only,a plurality of inlets formed on the upper surface thereof for allowing apenetration of the said reactive gas flow channels thereto with hermeticsealing at joints of the said inlets, a plurality of exits for saidreactive gas flow channels and a plurality of exits for said purge gasformed on the bottom surface thereof, and said exit for purge gas havinga diameter smaller than that of said exit for the reactive gas flowchannel, and wherein each reactive gas flow channel of the reactive gasshowerhead module passes through the said inner space of the purge gasshowerhead module.
 40. An apparatus for chemical vapor deposition (CVD)with a showerhead according to claim 39, wherein the purge gas exit is0.8 mm˜1.4 mm in diameter and the reactive gas flow channel exit is 3.5mm˜5 mm in diameter, and wherein the purge gas exit injects only thepurge gas and the reactive gas flow channel exit injects the purge gasby surrounding the lower end of the reactive gas flow channel.
 41. Anapparatus for chemical vapor deposition (CVD) with a showerheadaccording to claim 34, further comprising: a reactive gas confiningmeans placed inside the reaction chamber and spaced apart from the innerwall and the roof of the reaction chamber at a distance, surrounding thesubstrate in a dome shape, the lower end of the reactive gas confiningmeans touching the bottom of the reaction chamber, the reactive gasconfining means having a plurality of fine holes thereon; a second purgegas supply port formed on the reaction chamber for supplying a secondpurge gas into a space between the reaction chamber and the reactive gasconfining means; and an exhaust port mounted inside the reactive gasconfining means for exhausting byproducts, wherein the showerhead isdisposed on the reactive gas confining means in such a way that the rimof the showerhead is placed along an opened area formed at the centralportion of the upper surface of the reactive gas confining means,whereby the bottom surface of the showerhead and the substrate are facedwith each other.
 42. An apparatus for chemical vapor deposition (CFD)with a showerhead according to claim 34, further comprising: a reactivegas confining means placed inside the reaction chamber and spaced apartfrom the inner wall and the roof of the reaction chamber at a distance,the reactive gas confining means having a cylindrical body surroundingthe substrate, a lower end portion touching the bottom of the reactionchamber, and a plurality of fine holes thereon, and a disc having alarge opening at the center, placed on the upper end portion of thecylindrical body thereof and touching the reaction chamber wall at therim; a second purge gas supply port formed on the reaction chamber forsupplying the second purge gas into a space between the reaction chamberand the reactive gas confining means; and an exhaust port mounted insidethe reactive gas confining means for exhausting byproducts, wherein saidshowerhead is disposed on the reactive gas confining means in such a waythat the rim of the showerhead is placed along an opened area formed atthe central portion of the upper surface of the reactive gas confiningmeans, whereby the bottom surface of the showerhead and the substrateare faced with each other.